Induction of experimental glomerulonephritis in the rat by homologous major urinary protein.

Repeated injections of the major urinary protein (MUP) in the homologous rat produced a rise in the serum γ-globulin level, a severe proteinuria toward the end of experiment, the appearance of circulating antibodies to the major urinary protein, a hyperactivity of the lymphoid structure of the spleen and lung and particularly, renal lesions. The glomeruli showed marked thickening of the endothelial basement membrane and adhesion of the tufts with the Bowman's capsule. There were also slight alterations in the tubular basement membranes. Immunochemical studies of the experimental kidney revealed the disappearance of the kidney major antigen which was immunologically identical with the major urinary protein. The significance of the presence of circulating antibodies to major urinary protein has been discussed in relation to the biochemical and morphological changes in experimental animals. It has also been suggested that urinary proteins derived from the kidney and liver could induce glomerular lesions in the renal structure by an immunological mechanism.